/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jmx.export.assembler;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;

/**
 * Subclass of {@code AbstractReflectiveMBeanInfoAssembler} that allows for
 * the management interface of a bean to be defined using arbitrary interfaces.
 * Any methods or properties that are defined in those interfaces are exposed
 * as MBean operations and attributes.
 *
 * <p>By default, this class votes on the inclusion of each operation or attribute
 * based on the interfaces implemented by the bean class. However, you can supply an
 * array of interfaces via the {@code managedInterfaces} property that will be
 * used instead. If you have multiple beans and you wish each bean to use a different
 * set of interfaces, then you can map bean keys (that is the name used to pass the
 * bean to the {@code MBeanExporter}) to a list of interface names using the
 * {@code interfaceMappings} property.
 *
 * <p>If you specify values for both {@code interfaceMappings} and
 * {@code managedInterfaces}, Spring will attempt to find interfaces in the
 * mappings first. If no interfaces for the bean are found, it will use the
 * interfaces defined by {@code managedInterfaces}.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @see #setManagedInterfaces
 * @see #setInterfaceMappings
 * @see MethodNameBasedMBeanInfoAssembler
 * @see SimpleReflectiveMBeanInfoAssembler
 * @see org.springframework.jmx.export.MBeanExporter
 * @since 1.2
 */
public class InterfaceBasedMBeanInfoAssembler extends AbstractConfigurableMBeanInfoAssembler
        implements BeanClassLoaderAware, InitializingBean {

    @Nullable
    private Class<?>[] managedInterfaces;

    /**
     * Mappings of bean keys to an array of classes
     */
    @Nullable
    private Properties interfaceMappings;

    @Nullable
    private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

    /**
     * Mappings of bean keys to an array of classes
     */
    @Nullable
    private Map<String, Class<?>[]> resolvedInterfaceMappings;


    /**
     * Set the array of interfaces to use for creating the management info.
     * These interfaces will be used for a bean if no entry corresponding to
     * that bean is found in the {@code interfaceMappings} property.
     *
     * @param managedInterfaces an array of classes indicating the interfaces to use.
     * Each entry <strong>MUST</strong> be an interface.
     * @see #setInterfaceMappings
     */
    public void setManagedInterfaces(@Nullable Class<?>... managedInterfaces) {
        if (managedInterfaces != null) {
            for (Class<?> ifc : managedInterfaces) {
                if (!ifc.isInterface()) {
                    throw new IllegalArgumentException(
                            "Management interface [" + ifc.getName() + "] is not an interface");
                }
            }
        }
        this.managedInterfaces = managedInterfaces;
    }

    /**
     * Set the mappings of bean keys to a comma-separated list of interface names.
     * <p>The property key should match the bean key and the property value should match
     * the list of interface names. When searching for interfaces for a bean, Spring
     * will check these mappings first.
     *
     * @param mappings the mappings of bean keys to interface names
     */
    public void setInterfaceMappings(@Nullable Properties mappings) {
        this.interfaceMappings = mappings;
    }

    @Override
    public void setBeanClassLoader(@Nullable ClassLoader beanClassLoader) {
        this.beanClassLoader = beanClassLoader;
    }


    @Override
    public void afterPropertiesSet() {
        if (this.interfaceMappings != null) {
            this.resolvedInterfaceMappings = resolveInterfaceMappings(this.interfaceMappings);
        }
    }

    /**
     * Resolve the given interface mappings, turning class names into Class objects.
     *
     * @param mappings the specified interface mappings
     * @return the resolved interface mappings (with Class objects as values)
     */
    private Map<String, Class<?>[]> resolveInterfaceMappings(Properties mappings) {
        Map<String, Class<?>[]> resolvedMappings = new HashMap<>(mappings.size());
        for (Enumeration<?> en = mappings.propertyNames(); en.hasMoreElements(); ) {
            String beanKey = (String) en.nextElement();
            String[] classNames = StringUtils.commaDelimitedListToStringArray(mappings.getProperty(beanKey));
            Class<?>[] classes = resolveClassNames(classNames, beanKey);
            resolvedMappings.put(beanKey, classes);
        }
        return resolvedMappings;
    }

    /**
     * Resolve the given class names into Class objects.
     *
     * @param classNames the class names to resolve
     * @param beanKey the bean key that the class names are associated with
     * @return the resolved Class
     */
    private Class<?>[] resolveClassNames(String[] classNames, String beanKey) {
        Class<?>[] classes = new Class<?>[classNames.length];
        for (int x = 0; x < classes.length; x++) {
            Class<?> cls = ClassUtils.resolveClassName(classNames[x].trim(), this.beanClassLoader);
            if (!cls.isInterface()) {
                throw new IllegalArgumentException(
                        "Class [" + classNames[x] + "] mapped to bean key [" + beanKey + "] is no interface");
            }
            classes[x] = cls;
        }
        return classes;
    }


    /**
     * Check to see if the {@code Method} is declared in
     * one of the configured interfaces and that it is public.
     *
     * @param method the accessor {@code Method}.
     * @param beanKey the key associated with the MBean in the
     * {@code beans} {@code Map}.
     * @return {@code true} if the {@code Method} is declared in one of the
     * configured interfaces, otherwise {@code false}.
     */
    @Override
    protected boolean includeReadAttribute(Method method, String beanKey) {
        return isPublicInInterface(method, beanKey);
    }

    /**
     * Check to see if the {@code Method} is declared in
     * one of the configured interfaces and that it is public.
     *
     * @param method the mutator {@code Method}.
     * @param beanKey the key associated with the MBean in the
     * {@code beans} {@code Map}.
     * @return {@code true} if the {@code Method} is declared in one of the
     * configured interfaces, otherwise {@code false}.
     */
    @Override
    protected boolean includeWriteAttribute(Method method, String beanKey) {
        return isPublicInInterface(method, beanKey);
    }

    /**
     * Check to see if the {@code Method} is declared in
     * one of the configured interfaces and that it is public.
     *
     * @param method the operation {@code Method}.
     * @param beanKey the key associated with the MBean in the
     * {@code beans} {@code Map}.
     * @return {@code true} if the {@code Method} is declared in one of the
     * configured interfaces, otherwise {@code false}.
     */
    @Override
    protected boolean includeOperation(Method method, String beanKey) {
        return isPublicInInterface(method, beanKey);
    }

    /**
     * Check to see if the {@code Method} is both public and declared in
     * one of the configured interfaces.
     *
     * @param method the {@code Method} to check.
     * @param beanKey the key associated with the MBean in the beans map
     * @return {@code true} if the {@code Method} is declared in one of the
     * configured interfaces and is public, otherwise {@code false}.
     */
    private boolean isPublicInInterface(Method method, String beanKey) {
        return ((method.getModifiers() & Modifier.PUBLIC) > 0) && isDeclaredInInterface(method, beanKey);
    }

    /**
     * Checks to see if the given method is declared in a managed
     * interface for the given bean.
     */
    private boolean isDeclaredInInterface(Method method, String beanKey) {
        Class<?>[] ifaces = null;

        if (this.resolvedInterfaceMappings != null) {
            ifaces = this.resolvedInterfaceMappings.get(beanKey);
        }

        if (ifaces == null) {
            ifaces = this.managedInterfaces;
            if (ifaces == null) {
                ifaces = ClassUtils.getAllInterfacesForClass(method.getDeclaringClass());
            }
        }

        for (Class<?> ifc : ifaces) {
            for (Method ifcMethod : ifc.getMethods()) {
                if (ifcMethod.getName().equals(method.getName()) &&
                        Arrays.equals(ifcMethod.getParameterTypes(), method.getParameterTypes())) {
                    return true;
                }
            }
        }

        return false;
    }

}
